This invention relates to rapid wash methods and apparatus for removing deposits from surfaces and more particularly to the cleaning of deposits from surfaces exposed to flue gases.
It is well known that enormous quantities of heat are wasted as flue gases from various manufacturing processes are vented to the atmosphere. It is also known to place heat exchangers in contact with the flue gases for recovering some of the heat which otherwise would be lost. The use of heat recovery techniques has been severely limited, however, because contaminants contained in flue gases foul the heat exchange equipment. For example, the contaminants form deposits on the heat transfer surfaces of the heat exchanger thereby drastically reducing the amount of heat which can be recovered from the flue gases. In heat recovery systems in which flue gases are passed through a distributor plate to preheat batch materials before introduction of the materials into a furnace, the perforated distributor plate which supports the batch in a fluidized bed becomes clogged with the contaminants. In particular, in the manufacture of glass, heat recovery distributor plates become clogged with deposits of sodium sulfate. This clogging restricts flow of the flue gases thereby increasing the pressure drop across the distributor plate and reducing heat transfer into the fluidized bed. Energy is therefore lost in two ways: (1) reduced heat transfer into the bed reduces total energy recovered, and (2) the increased pressure drop results in higher power consumptions in flue gas blowers.
In order to use heat recovery techniques effectively in a flue gas environment, rigid maintenance schedules must be followed to clean the deposits from the heat exchange apparatus. In addition, other equipment which is exposed to flue gases must be cleaned or its operation will be impaired. As an example, air pollution control equipment which is placed in a flue to reduce contaminants often becomes coated with the contaminants thereby rendering the equipment relatively ineffective because of the build-up of deposits.
Known techniques for cleaning the surfaces of heat recovery equipment are generally cumbersome and/or labor intensive. One known technique uses brushes, movable on tracks, to mechanically clean the heat transfer surfaces. Other methods include use of air lances to direct a high velocity jet of air against the coated surfaces, shot blasting, steam cleaning and vacuum cleaning. Air lances are generally moved manually to effect cleaning. These methods often cannot be used in situ as the manufacturing process proceeds thereby necessitating periodic shutdowns for maintenance.
It is therefore an object of this invention to provide apparatus and method for cleaning, in situ, the surfaces of heat exchange and other equipment during exposure to flue gases.
It is a further object of this invention to provide such apparatus which is uncomplicated, inexpensive and easty to construct and maintain.
It is a further object of this invention to provide apparatus for cleaning heat exchange and other equipment without interrupting the manufacturing process.